Numerous electronic circuits require protection from damage due to electrostatic discharge (ESD) caused by rapid discharge of static electricity from one conductor to another having a different potential. ESD can damage integrated circuits in computers, communication equipment, and countless other types of electronic equipment. Semiconductor circuits and components built to provide ESD protection are conventionally implemented using components such as Shockley diodes, thyristors, latches, silicon controlled rectifiers (SCR) and metal gate field oxide (MGFO) devices. These conventional devices provide ESD protection between two terminals, and are typically constructed to snapback at a particular voltage and current, which may be too high for satisfactory ESD protection, and which is dictated by the doping levels of the diffusions that break down.
The ESD protection devices conventionally available generally suffer from lack of control of the breakdown voltage and critical voltage, due to physical design parameters. Conventional devices also rely on the avalanche breakdown of a surface junction, which can drift over repeated ESD strikes. With the advent of complex electronic circuits and smart power integrated circuits (ICs), design requirements now require even lower breakdown and snapback voltages for ESD protection, which are also stable over time. Devices that can snapback at a low voltage and current are finding an increasing need in applications including automotive and residential electronics. Since conventional ESD protection fails to handle sufficiently low snapback voltages and currents, a snapback voltage requirement for a particular device may require having to design a new device.
Therefore, a need exists to provide an ESD protection device that snaps back at a tightly controlled low voltage and current, which are stable over time. Further, such a device structure should be flexible enough to provide varying ESD properties without significant redesign of the device structure or addition/deletion of a significant number of doping regions.